The invention discloses a multifunctional electric recirculating ball steering system of a commercial vehicle and a control method thereof. The multifunctional electric recirculating ball steering system comprises an electric power module, a mechanical transmission module and a control module; the electric power module comprises a double-rotor motor module and a power assisting motor. The mechanical transmission module comprises a steering wheel, a steering shaft, a coupler, a recirculating ball steering gear, a gear sector, a gear sector shaft, a steering straight pull rod, a steering transverse pull rod, a steering knuckle arm, a left trapezoidal arm, a right trapezoidal arm, a left steering knuckle, a right steering knuckle, a left wheel and a right wheel. The control module comprises an electronic control unit, a torque sensor, a vehicle speed sensor, an angle sensor and a current sensor. According to the invention, the high reduction ratio capability of the recirculating ball steering gear is fully exerted, the power assisted torque of the system is maximized, the electric power assisted function is realized, the system is simplified, and the reliability of the system is ensured while the drive-by-wire function is provided.